This invention relates to a flow regulator for hydraulic circuits, which is designed to control the flow of a fluid between a source which feeds it at a feed pressure, and a user device in which the fluid is at a utilisation pressure which depends on the operating conditions of said device.
The regulator according to the invention is able both to continuously control the flow towards the user device without energy losses being produced consequent on the discharge of high pressure fluid flows, and to prevent too high overpressures being generated in the circuit, which could cause damage.
Flow regulation in known hydraulic systems (for example for controlling the equipment of earth moving machines, tractors or the like), is attained by varying the degree of closure of the delivery port of a slide valve, and discharging the excess fluid through a pressure relief valve. This latter valve is normally kept in its rest position, in which it completely closes the passage port between the feed chamber and discharge, by resilient means, and the valve is made to open when the fluid pressure on an active face thereof exceeds the set value of the force generated by said resilient means, so opening the valve.
In regulators of this type, there is a serious drawback due to the fact that the fluid which acts on the said active surface of the valve, and of which the pressure can be very high depending obviously on the maximum utilisation pressure, is fed to discharge so dispersing a rather high quantity of energy.